Note: Marks ending in U are for container owners; marks ending in X are not common carriers; marks ending in Z are for trailers without flanged wheels. All other marks are of common-carrier railroads.

P

• PACY - Prairie Central Railway
• PAE - Peoria and Eastern Railway; Conrail
• PAL - Paducah and Louisville Railway
• PAM - Pittsburgh, Allegheny and McKees Rocks Railroad
• PARX - Pan American Railway Company
• PARY - Prairie Trunk Railway
• PAS - Pan Am Southern
• PAUT - Pennsylvania and Atlantic Railroad; Conrail
• PAXX - Passenger Railcar Services Corporation
• PBFX - IBP, Inc.; Tyson Foods
• PBL - Philadelphia Belt Line Railroad
• PBLX - Pillsbury
• PBNE - Philadelphia, Bethlehem and New England Railroad
• PBR - Patapsco and Back Rivers Railroad
• PBRR - Prairie Belt Railroad
• PBVR - Port Bienville Railroad
• PC - Penn Central; Norfolk Southern
• PCA - Penn Central; Norfolk Southern
• PCB - Penn Central; Norfolk Southern
• PCCX - Peabody Coal Company
• PCEX - GE Rail Services
• PCFX - Pacific Car and Foundry Company
• PCIX - Shippers Car Line; ACF Industries
• PCMX - Petro-Chem Marketing Company
• PCN - Point Comfort and Northern Railway
• PCRC - Panama Canal Railway Company; Kansas City Southern Railway
• PCSX - GE Rail Services
• PCTX - Pioneer Cement Company of Texas
• PCY - Pittsburgh, Chartiers and Youghiogheny Railway
• PDQX - Castle Capital Corporation
• PE - Pacific Electric Railway; Conrail
• PECX - Pekin Energy Company
• PENX - Penford Products Company
• PEPX - Potomac Electric Power Company
• PER - Port Everglades Railway
• PF - Pioneer and Fayette Railroad
• PFE - Pacific Fruit Express; Union Pacific Railroad
• PFM - Power, Fluid & Metals
• PGDX - Procter and Gamble Manufacturing Company
• PGE - Pacific Great Eastern Railway; British Columbia Railway; Canadian National Railway
• PGER - Pacific Great Eastern Railway; British Columbia Railway; Canadian National Railway
• PGEX - Portland General Electric Company
• PGHX - Trinity Rail Management, Inc.
• PGMX - Procter and Gamble Manufacturing Company
• PGR - Progressive Rail
• PHCR - Port Colborne Harbour Railway
• PHD - Port Huron and Detroit Railroad; Chessie System; CSX Transportation
• PHL - Pacific Harbor Line
• PI - Paducah and Illinois Railroad
• PICK - Pickens Railroad
• PINX - Pinnacle Polymers
• PJR - Port Jersey Railroad
• PLCX - Pullman Leasing Company; GE Capital Railcar Services
• PLE - Pittsburgh and Lake Erie Railroad; New York Central Railroad; Penn Central; Conrail; CSX Transportation (after Conrail breakup)
• PLEX - PLM, Inc.
• PLLU - Polynesia Line
• PLLZ - Polynesia Line
• PLMX - PLM International
• PLWX - GE Capital Railcar Services
• PM - Pere Marquette Railway; Chesapeake and Ohio Railway; Chessie System; CSX Transportation
• PMLX - Prairie Malt, Ltd.
• PMRX - Progress Metal Reclamation Company
• PN - Piedmont and Northern Railway; Seaboard Coast Line; CSX Transportation
• PN - Pennsylvania Northeastern Railroad
• PNRW - Piedmont and Northern Railway (division of Patriot Rail Corporation)
• PNWR - Portland and Western Railroad
• PNWX - PNW Railcars, Inc.
• POHC - Pittsburgh and Ohio Central Railroad
• POTB - Port of Tillamook Bay Railroad
• PPAX - PCS Phosphate Company
• PPCX - American Association of Private Railroad Car Owners
• PPGX - PPG Industries, Inc.
• PPHX - PCS Phosphate Company
• PPLX - Pennsylvania Power and Light Company
• PPNX - PCS Phosphate Company
• PPRX - Phillips Petroleum Company
• PPU - Peoria and Pekin Union Railway
• PRCX - 20th Century Fox
• PRGX - ProGold, LLC
• PRL - Penn Eastern Rail Lines, Inc.; East Penn Railway
• PRLX - Progress Rail Services Corporation
• PRMU - Puerto Rican Maritime Shipping Authority
• PROX - Procor
• PRR - Pennsylvania Railroad; Penn Central; Norfolk Southern
• PRRX - Norfolk Southern
• PRSL - Pennsylvania-Reading Seashore Lines; Norfolk Southern
• PRSX - Progress Rail Services Corporation
• PS - Pittsburg and Shawmut Railroad
• PSCX - Public Service Company of Colorado
• PSIX - Pacific Steel, Inc
• PSL - Peabody Short Line; Illinois Central Railroad; Canadian National Railways
• PSPX - Phillips Petroleum Company
• PSR - Pittsburg and Shawmut Railroad
• PTM - Portland Terminal Company; Maine Central Railroad; Pan Am Railways
• PTEX - Canpotex
• PTLX - Pullman Transport Leasing; GE Rail Services
• PW - Providence and Worcester Railroad